Should I forget this 9-3?

I'm looking at a 2002 9-3 and today found this...

119k miles, cool air, power windows, sunroof all work, had to jump-start it with my truck.

It started right up and coughed and stumbled a couple of times, but then smoothed out and idled nicely.

As soon as it started, though I saw smoke coming from the oil fill and pulled the cap and saw a steady stream of smoke from there.

Seller said on the phone it had a freeze plug out and bad turbo, would run but not hold water.

I filled the coolant tank to half full and that never dropped in approx. 10 minutes of idling. I saw no leaks underneath.

I connected my scan tool and got a code for low voltage on O2 sensor - no biggie - and "incorrect gear ratio" - on an automatic?

When I cleared those codes, the car shut off. I gave the key back and left, but I'm drawn to the car for some reason - as a toy, not a daily driver by any means.

So, I've read a few opinions about the smoke from oil fill, but combined with everything else, does anyone here have any ideas?

Thanks!